The present invention relates to a unique valve assembly structure and more particularly to a valve assembly structure for electrically actuated expansion valves for refrigeration systems in which there is constant incremental flow rate control.
Electrically actuated expansion valves for controlling fluid flow in refrigerant systems are generally well known in the refrigeration art, attention being directed to tho motor actuated expansion valve disclosed in U.S. Pat. No. 4,986,085, issued to James C. Tischer on Jan. 22, 1991 and to the solenoid actuated expansion valve disclosed in U.S. Pat. No. 5,120,018, issued to John D. Lamb on Jun. 9, 1992. These and other past fluid control valves, particularly those employed as expansion valves in fluid refrigeration systems, have presented flow control problems involving comparatively high friction seating with accompanying stem sticking, undesirable energy utilization, and frequent wear and replacement. Furthermore, inaccurate shut-off due to valve stem sticking, and high friction wear, as well as limited usage over large temperature ranges, have led to undesirable fluid leakages in many of the previous refrigerant systems with undesirable damages to other parts in the refrigerant systems--often necessitating frequent and costly parts replacement.
The present invention recognizing the limitations of past valve assembly structures, provides a unique valve assembly structure which, although it has novel features readily usable with valve stems in a number of fluid control environments, is particularly usable with expansion valves for bi-flow heat pumps. The straightforward and economical valve structure of the present invention minimizes fluid leakage, reduces energy consuming torque and other energy requirements by providing low friction contact valve seating with minimal valve seat wear. At the same time, the novel structure of the present invention assures full closure of the valve stem with an optimum sealing surface and without undesirable valve sticking. The present invention further provides valve stem operation over a broad temperature range with minimal expansion--contraction and without undesirable longitudinal movement or rotation of the unique, straightforward, yet critical valve stem parts included in the unique valve structure assembly.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.